A source said: “There’s an investigation taking place, there’s obviously work being done and there’s intelligence.

“The Deely family are being briefed in relation to all matters in connection with the search and the ongoing operation. It is absolutely [the biggest lead] so far.”

Trevor went missing in the early hours of December 8, 2000, while he was walking home from a Christmas party in Dublin city centre.

The last known footage of the man from Naas, Co Kildare, shows him walking towards Haddington Road under a large umbrella at 4.14am.

Gardai are now probing if a known criminal met Trevor in the Baggot Street area by chance.

The site gardai are believed to be searching as part of the Trevor Deely investigation (Picture: Emma McMenamy)

One theory is he was murdered and dumped in the remote area.

The source added: “It’s all forming part of this investigation.

“It’s a protracted investigation, it’s ongoing, it has never closed and this is just another strand to it.

“It’s like every operation. But we are hopeful of a conclusion.”

A detailed examination of the area, which is being treated as a crime scene after the receipt of the new information, is likely to take up to two weeks. A sniffer dog and up to 20 officers are involved.

Gardai are not focusing on one particular area but are trawling as much of the woodland and scrub on the site as they can.

Yesterday officers cleared away large amounts of thick vegetation ahead of a dig expected to begin today. The search is being overseen by a forensic archaeologist.